Reducing a creature's toughness
Before we take a look at some of the colorless spells we will be seeing, lets take a look the card that will be the catalyst to get this party started, Herald of Kozilek
Keeping your best creature post-wrath is a delicious bonus
Intrepid Rabbit Intrepid Rabbit is another solid enough common that pumps something when it comes in, but it also scales nicely with the game thanks to the offspring mechanic
This often creates two or more colored mana on turn one, and continues to scale throughout the game with no downside or additional costs at untap
Jetfire has an interesting game plan, +1/+1 counters, and artifacts in Mono-blue This is a hard sell, but if you can pull it off, extra mana generation is always powerful